TORONTO (REUTERS) - Emergency braking was behind the derailment of a train hauling propane and crude oil early on Saturday, the Transportation Safety Board of Canada said on Tuesday.
In its first assessment of the accident, the TSB said the westbound Canadian National Railway mixed freight train had an "undesired emergency brake application" in Gainford, Alberta and 13 cars carrying dangerous goods derailed.
The explosion and fire that followed forced some 100 people from their homes.
The first four of the derailed cars carried crude oil, which did not catch fire, and the other nine contained liquefied petroleum gas, or propane, some of which caught fire after an explosion.
"Sparks and flames were visible to the crew. No injuries were reported," said the report from investigator James Carmichael.
The accident again focused attention on the safety of the transportation of hazardous material by rail.
This summer, a train hauling crude oil derailed and exploded in the Quebec town of Lac-Megantic, killing 47 people in North America's deadliest rail accident in two decades.
The TSB report did not explain how or why the emergency brakes were activated on the 134-car train. CN Railway, Canada's largest rail operator, was not immediately available for comment.
The accident closed CN's main line linking Alberta with the Pacific coast, with likely delays to some shipments.
CN reports its quarterly results after the market closes on Tuesday. Analysts mostly expect modest gains from year ago profit levels.